U.S. patent application number 11/815512 was filed with the patent office on 2009-02-05 for recording ink, ink set, ink cartridge, ink record, inkjet recording apparatus and inkjet recording method.
This patent application is currently assigned to Ricoh Company, Ltd.. Invention is credited to Hiroshi Adachi, Masanori Hirano, Akihiko Matsuyama.
Application Number | 20090035468 11/815512 |
Document ID | / |
Family ID | 36777367 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090035468 |
Kind Code |
A1 |
Matsuyama; Akihiko ; et
al. |
February 5, 2009 |
RECORDING INK, INK SET, INK CARTRIDGE, INK RECORD, INKJET RECORDING
APPARATUS AND INKJET RECORDING METHOD
Abstract
It is an object of the present invention to provide a recording
ink which contains at least a pigment, a dispersant, a
water-soluble solvent, a wetting agent and water, wherein the
pigment contains at least one of diketopyrrolopyrrole red pigment
and phthalocyanine green pigment in order to obtain a recording ink
and ink set which excel in discharge stability with no head
clogging during printing and can obtain high quality images with
good color tone on the regular paper as well as on an exclusive
recording paper; and ink cartridge, ink record, inkjet recording
apparatus and inkjet recording method which utilize the recording
ink and ink set respectively.
Inventors: |
Matsuyama; Akihiko;
(Kanagawa, JP) ; Hirano; Masanori; (Kanagawa,
JP) ; Adachi; Hiroshi; (Kanagawa, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Ricoh Company, Ltd.
Tokyo
JP
|
Family ID: |
36777367 |
Appl. No.: |
11/815512 |
Filed: |
February 2, 2006 |
PCT Filed: |
February 2, 2006 |
PCT NO: |
PCT/JP2006/302199 |
371 Date: |
October 30, 2007 |
Current U.S.
Class: |
427/256 ;
106/31.78; 347/100; 427/457; 524/88; 524/92 |
Current CPC
Class: |
C09D 11/40 20130101 |
Class at
Publication: |
427/256 ;
106/31.78; 524/88; 524/92; 427/457; 347/100 |
International
Class: |
C09D 11/02 20060101
C09D011/02; C09D 11/10 20060101 C09D011/10; B05D 5/00 20060101
B05D005/00; G01D 11/00 20060101 G01D011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 4, 2005 |
JP |
2005-029382 |
Sep 28, 2005 |
JP |
2005-283101 |
Claims
1. A recording ink comprising: a pigment, a dispersant, a
water-soluble solvent, a wetting agent, and water, wherein the
pigment comprises at least one of diketopyrrolopyrrole red pigment
and phthalocyanine green pigment.
2. The recording ink according to claim 1, wherein the
diketopyrrolopyrrole red pigment is at least one selected from C.
I. pigment red 254, C. I. pigment red 255, C. I. pigment red 264
and C. I. pigment red 272.
3. The recording ink according to claim 1, wherein the
phthalocyanine green pigment is at least one selected from C. I.
pigment green 7 and C. I. pigment green 36.
4. The recording ink according to claim 1, wherein the dispersant
is at least one of the compounds expressed by Structural Formulas
(11) and (12):
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.k--SO.sub.3M.sup.1 Structural
Formula (11) in which A.sup.1 represents one of an alkyl group
having 8 to 12 carbon atoms and which may be branched, an aryl
group having 6 to 18 carbons atoms, a benzyl group, a styrenated
phenol group, a distyrenated phenol group and a .beta.-naphthyl
group; k represents an integer of 5 to 30, and M.sup.1 represents
one of an alkali metal, ammonium, phosphonium and alkanolamine;
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.i--H Structural Formula (12) in
which A.sup.1 represents one of an alkyl group having 8 to 12
carbon atoms and which may be branched, an aryl group having 6 to
18 carbon atoms, a benzyl group, a styrenated phenol group, a
distyrenated phenol group and a .beta.-naphthyl group; and i
represents an integer of 20 to 60.
5. The recording ink according to claim 1, wherein 1 part by mass
to 100 parts by mass of the dispersant is added per 100 parts by
mass of the pigment.
6. The recording ink according to claim 1, wherein the recording
ink comprises water-dissolved material or water-dispersed material
having at least one of an acrylic resin, a methacrylic resin, a
polyurethane resin and a polyester resin, wherein the resin has a
mass-average molecular weight of 5,000 to 100,000 and an acid value
is of 50 KOHmg/g to 200 KOHmg/g.
7. The recording ink according to claim 1, wherein the mass (X) of
the dispersant and the mass (Y) of the solid content of the
water-dissolved material or the water-dispersed material of at
least one of acrylic resin, methacrylic resin, polyurethane resin
and polyester resin in the recording ink satisfies the equation:
Y/X.ltoreq.1.
8. The recording ink according to claim 1, wherein the wetting
agent is selected from 2-ethyl-1,3-hexanediol and
2,2,4-trimethyl-1,3-pentanediol.
9. The recording ink according to claim 1, wherein the
water-soluble solvent is at least one selected from glycerin,
diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol,
triethylene glycol, 1,6-hexanediol, propylene glycol,
1,5-pentanediol, dipropylene glycol and trimethylol propane.
10. The recording ink according to claim 1, wherein the recording
ink comprises a fluorochemical surfactant, and the fluorochemical
surfactant is at least one selected from perfluoroalkyl sulfonates,
perfluoroalkyl carbonates, perfluoroalkyl ethyleneoxide adducts and
perfluoroalkyl betaines.
11. The recording ink according to claim 1, wherein the recording
ink comprises polymer particles which have a volume average
particle diameter of 5 nm to 200 nm, a film-forming performance
after printing on a recording medium and a minimum film-forming
temperature of 30.degree. C. or less.
12. An ink set comprising: a recording ink which comprises: a
pigment, a dispersant, a water-soluble solvent, a wetting agent,
and water, in which the pigment comprises at least one of
diketopyrrolopyrrole red pigment and phthalocyanine green pigment,
wherein a red ink of 90% or more duty and a magenta ink of less
than 10% duty are used simultaneously for printing a red color of
90% or more ink duty, and a red ink of 90% or more duty and a
yellow ink of less than 10% duty are used simultaneously for
printing a red color of less than 90% ink duty.
13. An ink cartridge comprising: a recording ink which comprises a
pigment, a dispersant, a water-soluble solvent, a wetting agent,
and water, in which the pigment comprises at least one of
diketopyrrolopyrrole red pigment and phthalocyanine green pigment,
wherein the recording ink is contained in a container.
14. An inkjet recording apparatus comprising: an ink drop discharge
unit configured to discharge recording ink drops by applying
stimulation to a recording ink to record an image, wherein the
recording ink comprises: a pigment, a dispersant, a water-soluble
solvent, a wetting agent, and water, wherein the pigment comprises
at least one of diketopyrrolopyrrole red pigment and phthalocyanine
green pigment.
15. The inkjet recording apparatus according to claim 14, wherein
the stimulation is at least one selected from heat, pressure,
vibration and light.
16. An inkjet recording method comprising: discharging ink drops by
applying stimulation to a recording ink to record an image, wherein
the recording ink comprises: a pigment, a dispersant, a
water-soluble solvent, a wetting agent, and water, in which the
pigment comprises at least one of diketopyrrolopyrrole red pigment
and phthalocyanine green pigment.
17. An inkjet recording method comprising: discharging ink drops by
applying stimulation to each recording ink in an ink set to record
an image, wherein the ink set comprises: a recording ink which
comprises: a pigment, a dispersant, a water-soluble solvent, a
wetting agent, and water, in which the pigment comprises at least
one of diketopyrrolopyrrole red pigment and phthalocyanine green
pigment, wherein the red ink of 90% or more duty and the magenta
ink of less than 10% duty are used simultaneously for printing red
color of 90% or more ink duty, and the red ink of 90% or more duty
and the yellow ink of less than 10% duty are used simultaneously
for printing red color of less than 90% ink duty.
18. The inkjet recording method according to claim 16, wherein the
stimulation is at least one selected from heat, pressure, vibration
and light.
19. The inkjet recording method according to claim 16, wherein a
red ink of 90% or more duty and a magenta ink of less than 10% duty
are used simultaneously for printing a red color of 90% or more ink
duty, and a red ink of 90% or more duty and a yellow ink of less
than 10% duty are used simultaneously for printing a red color of
less than 90% ink duty.
20. An ink record comprising: an image recorded on a recording
medium using a recording ink which comprises: a pigment, a
dispersant, a water-soluble solvent, a wetting agent, and water, in
which the pigment comprises at least one of diketopyrrolopyrrole
red pigment and phthalocyanine green pigment.
Description
TECHNICAL FIELD
[0001] The present invention relates to recording ink and ink set
which excel in discharge stability with no head clogging during
printing and can obtain high quality images with good color tone on
the regular paper as well as on an exclusive recording paper; ink
cartridge, ink record, inkjet recording apparatus and inkjet
recording method which utilize the recording ink and ink set
respectively.
BACKGROUND ART
[0002] Recently, inkjet printers have been rapidly diffused for its
advantageous properties such as low noise and low running cost and
color printers which are printable on the regular paper have been
actively put into the market. However, satisfying all the
properties required such as color reproducibility, endurance, light
stability, drying property, feathering and color bleed of images,
duplex printing ability, discharge stability, and the like is very
difficult and inks are therefore selected depending on the
preferred but property corresponding to the purpose.
[0003] The inks used for inkjet printers in general consist mainly
of water and contain colorant and humectant such as glycerin, and
the like for anticlogging. Dyes are used as colorant for its
excellent color-producing property and stability. However, light
stability and waterproofness, etc. of the images produced by
dye-based inks are not satisfactory. Waterproofness may be improved
somehow by upgrading the inkjet recording paper containing ink
absorber layer, however, it is unsatisfactory for the regular
paper.
[0004] Recently, a pigment ink in which a pigment such as organic
pigment, carbon black, and the like instead of dyes is dispersed in
water or an aqueous medium is being investigated for use. Examples
of general method for producing pigment dispersion ink include high
speed agitation by homogenizers, kneading-dispersion machines using
balls such as bead mill or ball mill, kneading-dispersion machines
using shear force such as roll mill, a method for preparing
dispersion liquid using ultrasound dispersion machines, etc. after
dissolving a dispersant in an aqueous medium and sufficiently
moistening by adding pigment particles. For example, a method for
improving discharge stability in which an organic pigment is
reduced to particles of 50 nm or less in diameter using specific
dispersant is disclosed in Patent Literatures 2 and 3. And an ink
for inkjet printing using specific organic pigment and anionic
dispersant is disclosed in Patent Literature 4.
[0005] Recording inks for inkjet printing with pigment particles of
50 nm to 150 nm in the volume average particle diameter are being
used in general. If the particle is larger than this size, it
causes clogging of nozzles and if it is smaller, storage stability
is significantly deteriorated. There are various dispersants from
surfactants of low molecular mass to polymer dispersants of high
molecular mass. A polymer dispersant excels in storage stability;
however, it is difficult to reduce the volume average particle
diameter of a pigment particle to less than 150 nm. On the other
hand, with a dispersant of low molecular mass, it is possible to
reduce the volume average particle diameter of a pigment particle
to 50 nm to 100 nm; however, storage stability may not be
satisfactory. Methods for adding water-soluble polymers are
proposed in Patent Literatures 1 and 6 as a method to compensate
for the lack of storage stability of dispersant of low molecular
mass.
[0006] And others include surface reforming pigment ink in which
the surface of the pigment particles are modified with carboxyl
group, carbonyl group, sulfone group and hydroxyl group, and the
like to give hydrophilic property for stable dispersion. A surface
reforming carbon black, a black-based pigment ink in which pigment
particles can be stably dispersed by introducing hydrophilic groups
to the surface of carbon black, has been developed and put in
practical use. A color pigment which can be stably dispersed has
also been developed for color pigment inks. However, these surface
reforming pigment inks have disadvantages of insufficient scratch
resistance and waterproofness on the regular paper and the
exclusive gloss paper.
[0007] An inkjet ink utilizing a dispersing element of
micro-capsule or emulsion type by which the pigment particles are
coated with resin has been proposed. Since the pigment particles
are coated solidly by resin, dispersion may be stable for a long
period and the discharge stability may improve somewhat, however,
it is difficult to produce a dispersion particle of small particle
diameter suitable for inkjet printing and there is a problem of
high cost because of complicated production process.
[0008] For example, an approach of adding fluorochemical surfactant
to the ink and letting it spread broadly and uniformly in a
concentric fashion after an ink droplet is applied on the paper to
improve filling of the spaces between dots of ink droplets and
saturation in order to improve saturation degradation of printed
images caused by large diameter of dispersion particles, has been
proposed in Patent Literatures 7 and 8.
[0009] When printing in red color with magenta and yellow inks, a
phenomenon may be observed in that the color tone differs depending
on the order of ink applied on the paper. The phenomenon becomes
prominent in the inkjet method in which printing is performed by
scanning an ink discharge head because application order is
reversed between outward and homeward path and it is not acceptable
especially in a region of high concentration of pigment inks.
Similarly, when printing in green color with yellow and cyan inks
or when printing in blue color with cyan and magenta inks,
bidirectional color difference may also occur. This has been
handled by setting a limitation on the bidirectional printing
making the printing speed to slow down.
[0010] Therefore in the Patent Literature 4, it is stated that the
bidirectional color difference can be decreased by utilizing an ink
having at least four different hue as a color ink. However, red,
green and blue inks are not used in this proposal and it is of
different ink set formation.
[0011] Moreover, when secondary colors of red, green and blue are
formed by using yellow, magenta and cyan inks, the text looks
blurred because all the dots are not filled and spaces are left at
the tone exceeding total amount control. When yellow ink is used
for the secondary color, the text still looks blurred because of
the low visibility of yellow color and the text quality is
deteriorated. Furthermore, when secondary color is formed, two
kinds of inks are applied in the same dot to form one tone and
double amount of total application is needed to express the same
tone as a single color ink. However, because the tone exceeding
total amount control cannot be expressed, the number of tone is
lessened and therefore not favorable.
[0012] A red ink can be produced by simply mixing magenta and
yellow inks. Bidirectional color difference, text quality and tone
property can be improved by utilizing the mixed red ink better than
utilizing two different colors. However, there is no difference in
saturation between the mixed red ink and two different colors;
therefore it is impossible to expand the region of color
reproduction.
[0013] Moreover, further improvement of saturation is possible by
utilizing single red pigment. Particularly, the red ink of high
saturation can be prepared by diketopyrrolopyrrole red pigment
(Patent Literature 5). Similarly, it is possible to achieve a color
tone of high saturation for green inks by utilizing single
phthalocyanine green pigment better than applying two colors.
However, there is an issue of tone gradually moving off to the
yellow side as the image density and saturation are increased when
utilizing an ink of diketopyrrolopyrrole red pigment. This
phenomenon becomes distinguishable around 90% ink duty and the hue
transition becomes greater in a region of high density and
saturation.
[0014] It is difficult to perform a stable dispersion in an aqueous
medium when single red pigment, green pigment and in particular
diketopyrrolopyrrole red pigment and phthalocyanine green pigment
are utilized. When they are employed as inks for inkjet printing,
particle diameter must be as small as approximately 100 nm or less
and it is necessary to select based on the compatibility with
dispersant and pigment or with additive water-soluble solvent in
order to retain the ink of small particle diameter under stable
condition for extended period.
[0015] Therefore, the recording ink and ink set in which
diketopyrrolopyrrole red pigment and phthalocyanin green pigment
with excellent color development can be stably dispersed in an
aqueous medium; properties remain the same after long storage; and
are suitable as red and green inks with appropriate discharge
stability by inkjet have not been made available in the present
situation.
[Patent Literature 1] Japanese Patent (JP-B) No. 3625595 (Japanese
Patent Application Laid-Open (JP-A) No. 09-263720)
[Patent Literature 2] JP-A No. 09-263722
[Patent Literature 3] JP-A No. 2002-088286
[Patent Literature 4] JP-A No. 2003-276300
[Patent Literature 5] JP-A No. 08-239610
[Patent Literature 6] JP-B No. 3618493
[Patent Literature 7] JP-A No. 2003-268274
[Patent Literature 8] JP-A No. 2003-335987
DISCLOSURE OF INVENTION
[0016] It is an object of the present invention to provide a
recording ink and ink set in which diketopyrrolopyrrole red pigment
and phthalocyanin green pigment with excellent color development
can be stably dispersed in an aqueous medium; properties remain the
same after long storage; and are suitable as red and green inks
with appropriate discharge stability by inkjet; and ink cartridge,
ink record, inkjet recording apparatus and inkjet recording method
which utilize the recording ink and ink set respectively.
[0017] Furthermore, it is an object of the present invention to
provide a recording ink and ink set which are capable of correcting
text quality and tone property degradation when secondary colors
are utilized; improving printing speed by reducing bidirectional
color difference; and has high saturation and wide region of color
reproduction with no hue change by adhesive amount even when single
red pigment is utilized; and ink cartridge, ink record, inkjet
recording apparatus and inkjet recording method which utilize the
recording ink and ink set respectively.
[0018] The recording ink according to the present invention
contains a pigment, a dispersant, a water-soluble solvent, a
wetting agent, and water wherein the pigment contains at least one
of diketopyrrolopyrrole red pigment and phthalocyanine green
pigment. By the present invention, it is possible to provide the
recording inks such as red and green inks having appropriate
discharge stability by inkjet in which diketopyrrolopyrrole red
pigment and phthalocyanin green pigment with excellent color
development can be stably dispersed in an aqueous medium and
properties remain the same after long storage.
[0019] The recording ink according to the present invention is
preferably having an aspect wherein the diketopyrrolopyrrole red
pigment is at least one selected from C. I. pigment red 254, C. I.
pigment red 255, C. I. pigment red 264 and C. I. pigment red 272,
wherein the phthalocyanine green pigment is at least one of C. I.
pigment green 7 and C. I. pigment green 36, and wherein the
dispersant is at least one of compounds expressed by following
Structural Formulas (11) and (12).
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.k--SO.sub.3M.sup.1 Structural
Formula (11)
[0020] In Structural Formula (11), A.sup.1 represents one of alkyl
group having carbon number 8 to 12 which may be branched, aryl
group having carbon number 6 to 18, benzyl group, styrenated phenol
group, distyrenated phenol group and .beta.-naphthyl group. "k"
represents an integer of 5 to 30. M.sup.1 represents one of alkali
metal, ammonium, phosphonium and alkanolamine.
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.i--H Structural Formula (12)
[0021] In Structural Formula (12), A.sup.1 represents one of alkyl
group having carbon number 8 to 12 which may be branched, aryl
group having carbon number 6 to 18, benzyl group, styrenated phenol
group, distyrenated phenol group and .beta.-naphthyl group. "i"
represents an integer of 20 to 60.
[0022] It is also preferable for the recording ink according to the
present invention to have an aspect wherein the loadings of the
dispersant is 1 part by mass to 100 parts by mass based on 100
parts by mass of the pigment, wherein the recording ink contains
water-dissolved material or water-dispersed material of at least
one of acrylic resin, methacrylic resin, polyurethane resin and
polyester resin, wherein the mass-average molecular weight of the
resin is 5,000 to 100,000 and the acid value is 50 KOHmg/g to 200
KOHmg/g, wherein the mass of dispersant (X) and the mass of solid
content (Y) of water-dissolved material or water-dispersed material
of at least one of acrylic resin, methacrylic resin, polyurethane
resin and polyester resin in the recording ink satisfies the next
equation, Y/X.ltoreq.1, wherein the wetting agent is one of
2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol, wherein
the water-soluble solvent is at least one selected from glycerin,
diethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol,
triethylene glycol, 1,6-hexanediol, propylene glycol,
1,5-pentanediol, dipropylene glycol and trimethylol propane,
wherein the recording ink contains a fluorochemical surfactant and
the fluorochemical surfactant is at least one of perfluoroalkyl
sulfonates, perfluoroalkyl carbonates, perfluoroalkyl ethyleneoxide
adducts and perfluoroalkyl betaines, and wherein the recording ink
contains a polymer particle with the volume average particle
diameter of 5 nm to 200 nm having a film-forming performance after
printing on a recording medium wherein the minimum film-forming
temperature is 30.degree. C. or less.
[0023] The ink set according to the present invention contains at
least the recording ink according to the present invention wherein
the red ink of 90% or more duty and the magenta ink of less than
10% duty are used simultaneously for printing red color of 90% or
more ink duty, and the red ink of 90% or more duty and the yellow
ink of less than 10% duty are used simultaneously for printing red
color of less than 90% ink duty.
[0024] The ink cartridge according to the present invention
contains a recording ink according to the present invention in a
container.
[0025] The ink cartridge is suitably used for printers of inkjet
recording.
[0026] It is possible to obtain high quality images with good color
tone on the regular paper as well as on an exclusive recording
paper with excellent discharge stability with no head clogging
during printing by performing printing using the ink contained in
the ink cartridge.
[0027] The inkjet recording apparatus according to the present
invention contains an ink drop discharge unit configured to
discharge recording ink drops to record an image by applying
stimulation to the recording ink according to the present
invention. In the inkjet recording apparatus, an image is formed by
the ink drop discharge unit which discharges the recording ink
drops by applying energy to the recording ink of the present
invention. As a result, it is possible to form high quality images
with good color tone on the regular paper as well as on an
exclusive recording paper with excellent discharge stability with
no head clogging during printing.
[0028] The inkjet recording apparatus according to the present
invention is preferably having an aspect wherein the stimulation is
at least one selected from heat, pressure, vibration and light.
[0029] The inkjet recording method according to the first
embodiment of the present invention contains ink drop discharge to
record an image by applying stimulation to the recording ink of the
present invention.
[0030] The inkjet recording method according to the second
embodiment of the present invention contains ink drop discharge to
record an image by applying stimulation to each recording ink in
the ink set of the present invention.
[0031] One of the inkjet recording methods according to the first
and second embodiment of the present invention is preferably having
an aspect wherein the stimulation is at least one selected from
heat, pressure, vibration and light.
[0032] The inkjet recording method according to the second
embodiment of the present invention is preferably having an aspect
wherein the red ink of 90% or more duty and the magenta ink of less
than 10% duty are used simultaneously for printing red color of 90%
or more ink duty, and the red ink of 90% or more duty and the
yellow ink of less than 10% duty are used simultaneously for
printing red color of less than 90% ink duty.
[0033] The ink record according to the present invention contains
an image recorded on a recording medium using the recording ink
according to the present invention. The high quality images with
good color tone are retained on the recording medium of the ink
record.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 is an external perspective view showing an exemplary
ink cartridge prior to loading in the recording apparatus of the
present invention.
[0035] FIG. 2 is a cross-sectional view showing the ink cartridge
of FIG. 1.
[0036] FIG. 3 is an outlined cross-sectional view showing an
exemplary serial-type inkjet recording apparatus having an ink
cartridge containing the ink of the present invention.
[0037] FIG. 4 is an external perspective view showing an exemplary
recording unit unified with a recording head.
[0038] FIG. 5A is a cross-sectional view of a regular paper during
recording in the outward direction (from C to Y) which shows a
condition of applied ink droplet when the ink droplet is discharged
to the regular paper using a recording head.
[0039] FIG. 5B is a cross-sectional view of a regular paper during
recording in the homeward direction (from Y to C) which shows a
condition of applied ink droplet when the ink droplet is discharged
to the regular paper using the recording head.
[0040] FIG. 6 is a view showing an exemplary ink record during
recording in the homeward direction of FIG. 5B.
[0041] FIG. 7 is a graph showing a relation between ink duty and
color difference (.DELTA.E*).
[0042] FIG. 8A is a view describing a calculation method of ink
duty in a predetermined region of image data in the image region of
a recording head.
[0043] FIG. 8B is a view describing a scanning method to calculate
ink duty by displacing each window one line at a time in the
scanning direction of the recording head.
[0044] FIG. 8C is a view describing a scanning method to calculate
ink duty by displacing each window per its length in the length
direction of a band.
[0045] FIG. 9 is a flow chart describing the performance when ink
duty of a predetermined region of image data in the image region is
being calculated.
BEST MODE FOR CARRYING OUT THE INVENTION
(Recording Ink)
[0046] The recording ink of the present invention contains at least
a pigment, a dispersant, a water-soluble solvent, a wetting agent
and water and also contains water-soluble and/or water-dispersable
resin, polymer particle, surfactant and other elements as
necessary.
--Pigment--
[0047] The pigment contains at least one of diketopyrrolopyrrole
red pigment and phthalocyanine green pigment and further contains
other pigments as necessary.
[0048] The diketopyrrolopyrrole red pigment is preferably at least
one selected from C. I. pigment red 254, C. I. pigment red 255, C.
I. pigment red 264 and C. I. pigment red 272.
[0049] The phtahlocyanine green pigment is preferably at least one
of C. I. pigment green 7 and C. I. pigment green 36.
[0050] Other pigments are not particularly limited and may be
selected accordingly. Examples of pigment for black color include
carbon blacks (C. I. pigment black 7) such as firness black, lamp
black, acetylene black, channel black, and the like, copper, iron
(C. I. pigment black 11), metals such as titanic oxide, organic
pigments such as aniline black (C. I. pigment black 1).
[0051] Carbon black is preferable for the pigment for black color.
The carbon black excels in color tone, waterproofness, light
stability and dispersion stability and is inexpensive.
[0052] Examples of pigment for colors include C. I. pigment yellow
1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53,
55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120,
128, 138, 150, 151, 153, 183; C. I. pigment orange 5, 13, 16, 17,
36, 43, 51; C. I. pigment violet 1 (rhodamine lake), 3, 5:1, 16,
19, 23, 38; C. I. pigment blue 1, 2, 15 (phthalocyanine blue),
15:1, 15:2, 15:3 (phthalocyanine blue), 16, 17:1, 56, 60, 63, and
the like.
[0053] Of these pigments, the one having high affinity with water
is preferably used.
[0054] Other pigments such as graft pigment of which the surface of
a pigment such as carbon is treated with resin, etc. and made
dispersible in water or processed pigment of which the surface of a
pigment such as carbon is added with functional group such as
sulfone group or carboxyl group, etc. and made dispersible in water
are also usable.
[0055] Moreover, it may be a pigment contained in a micro-capsule
and made dispersible in water.
[0056] The volume average particle diameter of the pigment in the
recording ink is preferably 20 nm to 200 nm and more preferably 50
nm to 150 nm. The loadings of solid content of dispersion particles
in the ink with pigment and dispersant combined is preferably 2% by
mass to 20% by mass and more preferably 4% by mass to 15% by
mass.
[0057] The loadings of the pigment in the recording ink is not
limited and may be adjusted accordingly. It is preferably 0.5% by
mass to 25% by mass and more preferably 2% by mass to 15% by mass.
When the loadings is less than 0.5% by mass, the image density is
decreased and the image would be without contrast. When the
loadings is more than 25% by mass, it is difficult to maintain
dispersion stability of the colorant and likely to cause clogging
of nozzles, etc. and reliability may be deteriorated.
--Dispersant--
[0058] The dispersant is not particularly limited and may be
selected from dispersants used for preparing pigment dispersion
liquid accordingly. Examples include polyacrylic acid,
polymethacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl
acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid
alkylester copolymer, styrene-acrylic acid copolymer,
styrene-methacrylic acid copolymer, styrene-acrylic acid-acrylic
acid alkylester copolymer, styrene-methacrylic acid-acrylic acid
alkylester copolymer, stylene-.alpha.-methylstyrene-acrylic acid
copolymer-acrylic acid alkylester copolymer, styrene-maleic acid
copolymer, vinylnaphthalene-maleic acid copolymer, vinyl
acetate-ethylene copolymer, vinyl acetate-aliphatic acid vinyl
ethylene copolymer, vinyl acetate-maleic acid ester copolymer,
vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic acid
copolymer, compounds expressed by following Structural Formulas
(11) and (12), and the like. These dispersants can be used alone or
in combination.
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.k--SO.sub.3M.sup.1 Structural
Formula (11)
[0059] In Structural Formula (11), A.sup.1 represents one of alkyl
group having carbon number 8 to 12 which may be branched, aryl
group having carbon number 6 to 18, benzyl group, styrenated phenol
group, distyrenated phenol group and .beta.-naphthyl group. "k"
represents an integer of 5 to 30. M.sup.1 represents one of alkali
metal, ammonium, phosphonium and alkanolamine.
A.sup.1-O--(CH.sub.2CH.sub.2O).sub.i--H Structural Formula (12)
[0060] In Structural Formula (12), A.sup.1 represents one of alkyl
group having carbon number 8 to 12 which may be branched, aryl
group having carbon number 6 to 18, benzyl group, styrenated phenol
group, distyrenated phenol group and .beta.-naphthyl group. "i"
represents an integer of 20 to 60.
[0061] Of these, it is preferable to use one of the compounds
expressed by Structural Formulas (11) and (12).
[0062] Examples of the compound expressed by Structural Formula
(11) include a compound expressed by following Structural Formula
(1). In particular, it is preferably the compound expressed by
Structural Formula (A).
##STR00001##
[0063] In Structural Formula (1), R.sup.1 represents one of alkyl
group having carbon number 1 to 12 which may be branched, benzyl
group, styryl group and distyryl group. R.sup.2 represents one of
hydrogen atom, alkyl group having carbon number 1 to 12 which may
be branched, benzyl group and styryl group. "j" represents an
integer of 5 to 20. M.sup.1 represents one of alkali metal,
ammonium, phosphonium and alkanolamine.
##STR00002##
[0064] Examples of compound expressed by Structural Formula (12)
include polyoxyethylene laurylether, and the like. Of these,
compounds expressed by following Structural Formulas (13) and (13')
are preferable.
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H Structural Formula
(13)
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.42H Structural Formula
(13')
[0065] The loadings of the dispersant is preferably 1 part by mass
to 100 parts by mass and more preferably 10 parts by mass to 50
parts by mass based on 100 parts by mass of the pigment. If the
loadings of the dispersant is too low, pigment may not be atomized
satisfactory and if it is too high, excess element not attached to
the pigment effect the ink properties leading to image blurring or
deterioration of waterproofness and wear resistance.
--Water-Soluble and/or Water-Dispersible Resin--
[0066] Storage stability of the recording ink of the present
invention may be improved by adding at least one of water-soluble
or water-dispersible material of acrylic resin, methacrylic resin,
polyurethane resin and polyester resin. It is possible to add resin
when dispersing pigment using a dispersion machine such as bead
mill or atrighter, etc. or together with water-soluble solvent or
surfactant, etc. when preparing the recording ink. It is preferable
to add resin when preparing the recording ink.
[0067] The acrylic resin is not particularly limited and may be
selected accordingly. Examples include polyacrylic acid, acrylic
acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester
copolymer, acrylic acid-acrylic acid alkylester copolymer,
styrene-acrylic acid copolymer, styrene-acrylic acid-acrylic acid
alkylester copolymer, stylene-.alpha.-methylstyrene-acrylic acid
copolymer, acrylic acid alkylester copolymer, vinyl acetate-acrylic
acid copolymer, and the like.
[0068] The methacrylic resin is not particularly limited and may be
selected accordingly. Examples include polymethacrylic acid,
styrene-methacrylic acid copolymer, styrene-methacrylic
acid-acrylic acid alkylester copolymer,
stylene-.alpha.-methylstyrene-acrylic acid copolymer, and the
like.
[0069] The polyurethane resin is not particularly limited and may
be selected accordingly. Examples include polyurethane resin made
soluble in water or dispersed in water by introducing hydrophilic
element such as carboxyl group, sulfone group, and the like in
urethane skeleton.
[0070] Commercially available polyurethane resin may be used and
examples include Hydran HW-970 and HW-940 by Dainippon Ink And
Chemicals, Inc., Takelac W-6010, W-6061 and W-5025 by Mitsui Takeda
Chemicals, Inc., SF-107M, SF-460, and the like by Dai-ichi Kogyo
Seiyaku Co., Ltd.
[0071] The polyester resin is not particularly limited and may be
selected accordingly. Examples include polyester resin made soluble
in water or dispersed in water by introducing hydrophilic element
such as carboxyl group, sulfone group, and the like into the side
chain of polyester skeleton.
[0072] Commercially available polyester resin may be used and
examples include Pesresin A-210, A-520, A-620, and the like by
Takamatsu Oil & Fat Co., Ltd.
[0073] The mass-average molecular weight of these resins is
preferably 5,000 to 100,000 and more preferably 10,000 to 30,000.
If the mass-average molecular weight is more than 100,000,
viscosity of the ink increases and the discharge from the inkjet
nozzle may become unstable. When it is less than 5,000, it is not
favorable because the effect on storage stability is lost.
[0074] Meanwhile, the mass-average molecular weight of the resin
can be measured by Gel Permission Chromatography (GPC).
[0075] It is preferable that the relation between the mass of
dispersant (X) and the mass of solid content (Y) of water-dissolved
or water-dispersed material of acrylic resin, methacrylic resin,
polyurethane resin and polyester resin in the recording ink of the
present invention is Y/X.ltoreq.1 and more preferably
Y/X.ltoreq.0.01 to Y/X.ltoreq.0.5. When the value of Y/X is larger
than 1, viscosity of the ink is high possibly causing a problem
during ink discharge.
--Water-Soluble Solvent--
[0076] The recording ink of the present invention uses water as a
liquid medium; however, a water-soluble solvent mentioned below is
used in order to prevent drying of the ink and to improve
dispersion stability, etc. These solvents have favorable effects
over solubility and prevention of injection-quality defects caused
by water evaporation.
[0077] Water-soluble solvent is not particularly limited and may be
selected accordingly. Examples include polyvalent alcohols,
polyvalent alcohol alkyl ethers, polyvalent alcohol aryl ethers,
nitrogen-containing heterocyclic compounds, amides, amines,
sulfur-containing compounds, propylene carbonate, ethylene
carbonate, other water-soluble solvents, and the like. These may be
used alone or in combination.
[0078] Examples of polyvalent alcohols include glycerin, diethylene
glycol, 1,3-butanediol, 3-methyl-1,3-butanediol, triethylene
glycol, propylene glycol, dipropylene glycol, trimethylol propane,
trimethylol ethane, ethylene glycol, tripropylene glycol,
tetraethylene glycol, hexylene glycol, polyethylene glycol,
polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol,
1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, petriol,
and the like.
[0079] Examples of polyvalent alcohol alkyl ethers include ethylene
glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene
glycol monomethyl ether, diethylene glycol monoethyl ether,
diethylene glycol monobutyl ether, tetraethylene glycol monomethyl
ether, propylene glycol monoethyl ether, and the like.
[0080] Examples of polyvalent alcohol arylethers include ethylene
glycol monophenyl ether, ethylene glycol monobenzyl ether, and the
like.
[0081] Examples of nitrogen-containing heterocyclic compound
include 2-pyrrolidone, N-methyl-2-pyrrolidone,
N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl imidazoledione,
s-caprolactam, .gamma.-butyrolactone, and the like.
[0082] Examples of amides include formamide, N-methyl formamide,
N,N-dimethyl formamide, and the like.
[0083] Examples of amines include monoethanol amine, diethanol
amine, triethanol amine, monoethyl amine, diethyl amine, triethyl
amine, and the like.
[0084] Examples of sulfur-containing compound include dimethyl
sulfoxide, sulfolane, thiodiethanol, and the like.
[0085] Other water-soluble solvents are preferably containing
sugars. Examples of sugars include monomeric sugars, two sugars,
oligosaccharides (including trisaccharide and tetrasaccharide) and
polysaccharides. Specific examples include glucose, mannose,
fructose, ribose, xylose, arabinose, galactose, maltose,
cellobiose, lactose, sucrose, trehalose, malt triose, and the like.
The polysaccharides stated here are defined as sugars in a broad
sense, which contain matters that broadly exist in the realm of
nature such as .alpha.-cyclodextrin, cellulose, and the like.
Derivatives of these sugars include reducing sugar of the above
sugars such as sugar alcohol expressed by General Formula:
HOCH.sub.2(CHOH)nCH.sub.2OH where "n" represents an integer of 2 to
5, saccharides such as aldonic acid, uronic acid, and the like,
amino acid, thio acid, and the like. Of these, sugar alcohol is
preferable and specific examples thereof include maltitol,
sorbitol, and the like.
[0086] Of these water-soluble solvent, glycerin, diethylene glycol,
1,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol,
1,6-hexanediol, propylene glycol, 1,5-pentanediol, dipropylene
glycol and trimethylol propane are particularly preferable in terms
of storage and discharge stability.
[0087] The mass ratio of the pigment to the water-soluble solvent
significantly affects the ink discharge stability from head. If the
blending quantity of humectant is relatively small even though the
solid content of pigment is large, water evaporation near the ink
meniscus of the nozzle progresses and may result in discharge
failure.
[0088] The loadings of water-soluble solvent in the recording ink
is preferably 10% by mass to 50% by mass and more preferably 15% by
mass to 35% by mass. The ratio of water-soluble solvent to the
solid content of pigment particle including dispersant is
preferably 0.67 to 12.5, more preferably 1.0 to 6.0 and most
preferably 2.0 to 4.0. The recording ink within this range provides
very favorable results in drying property, storage test or
reliability test.
--Wetting Agent--
[0089] It is preferable to use polyol compounds having carbon
number 8 to 11 or glycol ether compounds as wetting agent.
[0090] Examples of polyol compounds having carbon number 8 to 11
include 2,5-dimethyl-2,5-hexanediol, 2-ethyl-1,3-hexanediol,
2,2,4-trimethyl-1,3-pentandiol, and the like. Of these,
2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentandiol are
particularly preferable.
[0091] Examples of glycol ether compounds include polyvalent
alcohol alkyl ether compounds, polyvalent alcohol arylether
compounds, and the like.
[0092] Examples of polyvalent alcohol alkyl ether compounds include
ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
diethylene glycol monomethyl ether, diethylene glycol monoethyl
ether, diethylene glycol monobutyl ether, tetraethylene glycol
monomethyl ether, propylene glycol monoethyl ether, and the
like.
[0093] Examples of polyvalent alcohol arylether compounds include
ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether,
and the like.
[0094] The loadings of wetting agent in the recording ink is not
particularly limited and may be selected accordingly and it is
preferably 0.5% by mass to 4% by mass.
--Surfactant--
[0095] The surfactant is not particularly limited and may be
selected accordingly. Preferred examples include anionic surfactant
and nonionic surfactant. Of these, fluorochemical surfactant is
particularly preferable. A surfactant which does not impair the
dispersion stability is selected depending on the combination of
nature of color material, humectant and water-soluble organic
solvent.
[0096] Examples of anionic surfactant include polyoxyethylene
alkylether acetate, dodecylbenzen sulfonate, sodium laurylate,
polyoxyethylene alkylether sulfonate, and the like.
[0097] Examples of nonionic surfactant include acetylene glycol
surfactant, polyol, glycol ether, polyoxyethylene alkylether,
polyoxyethylene alkylester, polyoxyethylene sorbitan fatty ester,
polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine,
polyoxyethylene alkylamide, acetylene glycol, and the like.
[0098] Examples of acetylene glycol surfactants include
2,4,7,9-tetramethyl-5-dithine-4,7-diol,
3,6-dimethyl-4-octine-3,6-diol, 3,5-dimethyl-1-hexane-3-ol,
compounds expressed by following Structural Formula (7), and the
like.
[0099] Commercially available acetylene glycol surfactants such as
Surfynol 104, 82, 465, 485 or TG by Air Products and Chemicals,
Inc. (U.S.A.) are usable and of these, Surfynol 465, 104 and TG are
particularly preferable for exhibiting appropriate printing
quality.
[0100] Preferred examples of anionic surfactant and nonionic
surfactant include surfactants expressed by following Structural
Formulas (2) to (7).
R.sup.3--O--(CH.sub.2CH.sub.2O).sub.hCH.sub.2COOM Structural
Formula (2)
[0101] In Structural Formula (2), R.sup.3 represents alkyl group
and the alkyl group having carbon number 6 to 14 which may be
branched is preferable. "h" represents an integer of 3 to 12. "M"
represents one selected from alkali metal ion, quaternary ammonium,
quaternary phosphonium and alkanolamine.
##STR00003##
[0102] In Structural Formula (3), R.sup.4 represents alkyl group
having carbon number 5 to 16 which may be branched. "M" represents
one selected from alkali metal ion, quaternary ammonium, quaternary
phosphonium and alkanolamine.
##STR00004##
[0103] In Structural Formula (4), R.sup.5 represents hydrocarbon
group and examples include alkyl group having carbon number 6 to 14
which may be branched. "k" represents an integer of 5 to 20.
##STR00005##
[0104] In Structural Formula (5) and (5'), R.sup.5 represents
hydrocarbon group. Each "L", "m", "n" and "p" represents an integer
of 1 to 20. Examples of hydrocarbon group include alkyl group
having carbon number 6 to 14 which may be branched.
##STR00006##
[0105] In Structural Formulas (6) and (6'), R.sup.6 represents
hydrocarbon group. Each "L", "m", "n" and "p" represents an integer
of 1 to 20. Examples of hydrocarbon group include alkyl group
having carbon number 6 to 14 which may be branched.
##STR00007##
[0106] In Structural Formula (7), each "q" and "r" represents an
integer of 0 to 40.
[0107] The fluorochemical surfactant is not particularly limited
and examples include perfluoroalkyl sulfonates, perfluoroalkyl
carbonates, perfluoroalkyl phosphoric ester, perfluoroalkyl
ethyleneoxide adducts, perfluoroalkyl betaines, perfluoroalkylamine
oxide, perfluoroalkylether compounds, and the like.
[0108] The commercially available fluorochemical surfactants are
usable and examples include SURFLON S-111, S-112, S-113, S-121,
S-131, S-132, S-141 and S-145 by Asahi Glass Co., Ltd., FLUORAD
FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430 and FC-431 by
Sumitomo 3M Limited, MEGAFAC F-470, F-1405 and F-474 by Dainippon
Ink & Chemicals, Inc., ZONYL TBS, FSP, FSA, FSN-100, FSN,
FSO-100, FSO, FS-300 and UR by DuPont Co., FT-110, 250, 251 and
400S by Neos Co., Ltd. Of these, FT-110, 250, 251 and 400S by Neos
Co., Ltd. are preferable for appropriate printing quality,
particularly the notable improvement of color developing ability
and level dyeing property on the paper.
[0109] When the fluorochemical surfactant is used in the recording
ink of the present invention, the surface tension of the recording
ink is further decreased allowing the recording ink to easily
penetrate into the recording medium after ink drops are applied to
the recording medium such as paper. Moreover, it allows the
fluorochemical surfactant to easily penetrate between aggregated
particles in the recording ink and works well for reducing
feathering or color bleed by separating aggregated particles and
preventing aggregation.
--Polymer Particle--
[0110] The recording ink of the present invention contains polymer
particles with the volume average particle diameter of 5 nm to 200
nm. The polymer particle is preferably having a film-forming
performance after printing on a recording medium and the minimum
film-forming temperature is 30.degree. C. or less.
[0111] The film-forming performance of polymer particle means when
a polymer particle is dispersed in water to form an emulsion, a
resin film is formed as the moisture of aqueous emulsion
evaporates.
[0112] In the ink composition into which the polymer particle is
added, a film is formed by evaporating the volatile element to
strongly fixate the color material (pigment) in the ink on the
recording medium. Therefore it is possible to form an image of
excellent scratch resistance and waterproofness.
[0113] Since the ink composition added with polymer particle forms
a film at a room temperature, the minimum film-forming temperature
of the polymer particle is preferably 30.degree. C. or less and
more preferably 10.degree. C. or less.
[0114] The minimum film-forming temperature can be measured
according to ISO 2115 or ASTM D2354.
[0115] The average particle diameter of polymer particle is
preferably 5 nm to 200 nm and more preferably 10 nm to 100 nm.
[0116] The polymer particle is not particularly limited and may be
obtained by known method. Examples include a method in which
unsaturated vinyl monomer is put in water where polymerization
catalyst and emulsifying agent exist and emulsion polymerization
takes place.
[0117] The loadings of polymer particle is preferably 0.5% by mass
to 20.0% by mass and more preferably 1.0% by mass to 5.0% by mass
relative to the total amount of the recording ink. When the
loadings of polymer particle is less than 0.5% by mass, scratch
resistance and waterproofness may not be satisfactory. When the
loadings of polymer particle is more than 20% by mass, viscosity
increase or polymer element fixation by drying may occur resulting
in unstable ink discharge and nozzle clogging.
--Other Elements--
[0118] Other elements are not particularly limited and may be
selected accordingly. Examples include defoamer, pH adjusting
agent, antiseptic and antifungal agent, rust-preventive agent,
antioxidant, UV ray absorber, chelating agent, oxygen absorbent,
light stabilizing agent, and the like.
[0119] The defoamer is not particularly limited and may be selected
accordingly. Suitable examples include silicone defoamer, polyether
defoamer, fatty ester defoamer, and the like. These may be used
alone or in combination. Of these, silicone defoamer is preferable
for its excellent foam breaking effect.
[0120] Examples of silicone defoamer include silicone defoamer of
oil type, compound type, self-emulsification type, emulsion type,
and modified silicone defoamer, and the like. Examples of modified
silicone defoamer include amino-modified silicone defoamer,
carbinol-modified silicone defoamer, methacryl-modified silicone
defoamer, polyether-modified silicone defoamer, alkyl-modified
silicone defoamer, higher fatty ester-modified silicone defoamer,
alkylene oxide-modified silicone defoamer, and the like. Of these,
silicone defoamer of self-emulsification type and emulsion type are
preferable in terms of usage in the recording ink which is an
aqueous medium.
[0121] Commercially available products can be used as defoamers and
examples include silicone defoamers by Shin-Etsu Chemical Co., Ltd.
such as KS508, KS531, KM72, KM85, and the like, silicone defoamers
by Dow Corning Toray Co., Ltd. such as Q2-3183A, SH5510, and the
like, silicone defoamers by Nippon Unicar Co., Ltd. such as SAG30,
and the like and defoamers of Asahi Denka Co., Ltd. such as Adeka
Nate series, and the like.
[0122] The loadings of defoamer in the recording ink is not limited
and may be selected accordingly. For example, it is preferably
0.001% by mass to 3% by mass and more preferably 0.005% by mass to
0.5% by mass.
[0123] When the defoamer is contained in the recording ink, it
exhibits appropriate storage or discharge stability. If the
loadings is less than 0.001% by mass, inclusion effect may not be
satisfactory. If it is more than 3% by mass, it is likely to be a
cause of clogging and reliability of the recording ink may be
deteriorated.
[0124] Examples of antiseptic and antifungal agent include sodium
dehydroacetate, sodium sorbate, 2-pyridinethiol-1-sodium oxide,
sodium benzoate, sodium pentachlorophenol, and the like.
[0125] The pH adjusting agent can stabilize dispersion condition
and discharge by retaining alkalinity of the ink. If pH is more
than 11, melting amount of inkjet head or ink supply unit is too
much leading to alteration, leakage or discharge failure of the
ink. It is preferable to add pH adjusting agent when pigment is
kneaded and dispersed in water with dispersant instead of adding it
with humectant and wetting agent after knead dispersion. It is
because dispersion may be destructed by adding depending on the pH
adjusting agent.
[0126] Examples of pH adjusting agent include alcohol amines such
as diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3 propandiol,
and the like, hydroxides of alkali metal element such as lithium
hydroxide, sodium hydroxide, potassium hydroxide, and the like,
hydroxides of ammonium such as ammonium hydroxide, quaternary
ammonium hydroxide, quaternary phosphonium hydroxide, carbonates of
alkali metal such as lithium carbonate, sodium carbonate, potassium
carbonate, and the like.
[0127] Examples of rust-preventive agent include acid sulfite,
sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium
nitrite, pentaerythritol tetranitrate, dicyclohexylammonium
nitrite, and the like.
[0128] Examples of antioxidant include phenolic antioxidant
including hindered phenol antioxidant, amine antioxidant, sulfur
antioxidant, phosphorous antioxidant, and the like.
[0129] Examples of phenolic antioxidant including hindered phenol
antioxidant include butylated hydroxyanisole,
2,6-di-tert-butyl-4-ethylphenol,
stearyl-.beta.-(3,5-di-tert-butyl-4-hydroxyphenol)propionate,
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
4,4'-butylidenebis(3-methyl-6-tert-butylphenol),
3,9-bis[1,1-dimethyl-2-[.beta.-(3-tert-butyl-4-hydroxy-5-methylphenyl)pro-
pionyloxy]ethyl]2,4,8,10-tetra oxaspiro[5,5]undecane,
1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]met-
hane, and the like.
[0130] Examples of amine antioxidant include
phenyl-.beta.-naphthylamine, .alpha.-naphthylamine,
N,N'-di-sec-butyl-p-phenylenediamine, phenothiazine,
N,N'-diphenyl-p-phenylenediamine, 2,6-di-tert-butyl-p-cresol,
2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol,
butylhydroxyanisol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol),
4,4'-butylidenebis(3-methyl-6-tert-butylphenol),
4,4'-thiobis(3-methyl-6-tert-butylphenol),
tetrakis[methylene-3(3,5-di-tert-butyl-4-dihydroxyphenyl)propionate]metha-
ne, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and
the like
[0131] Examples of sulfur antioxidant include
dilauryl-3,3'-thiodipropionate, distearylthiodipropionate,
laurylstearylthiodipropionate, dimyristyl-3,3'-thiodipropionate,
distearyl .beta.,.beta.'-thiodipropionate,
2-mercaptobenzoimidazole, dilaurylsulfide, and the like.
[0132] Examples of phosphorous antioxidant include
triphenylphosphite, octadecylphosphite, triisodecylphosphite,
trilauryltrithiophosphite, trinonylphenylphosphite, and the
like.
[0133] Examples of UV ray absorber include UV ray absorber based on
benzophenone, benzotriazole, salicylate, cyanoacrylate, nickel
complex salt, and the like.
[0134] Examples of benzophenone-based UV-ray absorber include
2-hydroxy-4-n-octoxybenzophenone,
2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone,
2,2',4,4'-tetrahydroxybenzophenone, and the like.
[0135] Examples of benzotriazole-based UV ray absorber include
2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole,
2-(2'-hydroxy-5'-methylphenyl)benzotriazole,
2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole,
2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole,
and the like.
[0136] Examples of salicylate-based UV ray absorber include
phenylsalicylate, p-tert-butylphenylsalicylate,
p-octylphenylsalicylate, and the like.
[0137] Examples of cyanoacrylate-based UV ray absorber include
ethyl-2-cyano-3,3'-diphenylacrylate,
methyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate,
butyl-2-cyano-3-methyl-3-(p-methoxyphenyl)acrylate, and the
like.
[0138] Examples of nickel complex salt-based UV ray absorber
include nickel-bis(octylphenyl)sulfide,
2,2'-thiobis(4-tert-octylferrate)-n-b utylamine nickel(II),
2,2'-thiobis(4-tert-octylferrate)-2-ethylhexylamine nickel(II),
2,2'-thiobis(4-tert-octylferrate)triethanolamine nickel(II), and
the like.
[0139] Examples of chelating agent include sodium ethylenediamine
tetraacetate, sodium nitrilotriacetate, sodium hydroxyethyl
ethylenediaminetriacetate, sodium diethylenetriaminepentaacetate,
sodium uramil diacetate, and the like.
[0140] The recording ink of the present invention is produced by
dispersing or dissolving at least one of diketopyrrolopyrrole red
pigment and phthalocyanine green pigment, dispersant, water-soluble
solvent, one of polyol compound having carbon number 8 to 11 and
glycolether compound, water and other elements as necessary in an
aqueous medium and further stirring-mixing as necessary. The
dispersion may be performed by sand mill, homogenizer, ball mill,
paint shaker, ultrasound dispersion apparatus, and the like and
stirring-mixing may be performed by a stirrer using normal
agitating blade, magnetic stirrer, high-speed dispersion apparatus,
and the like.
[0141] The coloring of the recording ink of the present invention
is not particularly limited and may be selected accordingly and
examples include yellow, magenta, cyan, black, and the like. It is
possible to form a multicolor image when recording is performed
using an ink set which uses two or more of these colors
simultaneously and it is also possible to form a full color image
when recording is performed by using an ink set which uses all
colors simultaneously.
[0142] The properties of recording ink of the present invention are
not particularly limited and surface tension, viscosity, electric
conductivity and pH are preferably in the following ranges.
[0143] The surface tension is preferably 35 mN/m or less at
20.degree. C.
[0144] The viscosity is preferably 2 mPas to 20 mPas and more
preferably 3 mPas to 10 mPas at 25.degree. C. If the viscosity is
less than 2 mPas, image may be blurred, and when it is more than 20
mPas, maintaining discharge stability may be difficult.
[0145] The electric conductivity is preferably 0.5 S/m or less and
more preferably 0.005 S/m to 0.4 S/m.
[0146] The pH is preferably 7 to 11.
(Ink Set)
[0147] The ink set of the present invention at least contains the
recording ink of the present invention and it is combined with at
least one of yellow ink, magenta ink, cyan ink and black ink.
[0148] Each yellow ink, magenta ink, cyan ink and black ink is not
particularly limited and may be selected from known inks
accordingly.
[0149] It is preferable for the ink set to use the red ink of 90%
or more duty and magenta ink of less than 10% duty simultaneously
for printing red color of 90% or more ink duty, and to use the red
ink of 90% or more duty and yellow ink of less than 10% duty
simultaneously for printing red color of less than 90% ink
duty.
[0150] The ink duty is a ratio of color material assigned in the
unit recording region and it is 100% maximum for primary color and
200% maximum for secondary color. The detail of ink duty will be
explained later.
[0151] The recording ink of the present invention can be suitably
used for printers having inkjet head such as piezo inkjet head
which discharges ink by altering the inner volume of ink flow path
by deforming the diaphragm forming wall face of the ink flow path
using a piezoelectric device as a pressure generating unit which
pressurizes the ink in the ink flow path (JP-A No. 02-051734),
thermal inkjet head which generates air bubbles by heating the ink
in the ink flow path using a heat element (JP-A No. 61-059911),
electrostatic inkjet head which discharges ink drops by altering
the inner volume of ink flow path by positioning diaphragm forming
wall face of the ink flow path and electrode to face each other and
generating electrostatic power between diaphragm and electrode to
deform the diaphragm (JP-A No. 06-071882).
[0152] The recording ink of the present invention can be suitably
used in various areas and is suitable for image forming apparatus
of inkjet printing such as printers, and the like. For example, it
can be used for printers having a function to facilitate print
fixation by heating the recording paper and the recording ink at
50.degree. C. to 200.degree. C. during printing or before and after
printing. It is especially suitable for use for ink cartridge, ink
record, inkjet recording apparatus and inkjet recording method of
the present invention.
(Ink Cartridge)
[0153] The ink cartridge of the present invention contains the
recording ink of the present invention in the container and other
members as necessary.
[0154] The container is not particularly limited and its form,
structure, size, material, and the like may be selected
accordingly. Suitable examples include a container at least having
an ink bag formed of aluminum laminated film, resin film, and the
like.
[0155] Next, ink cartridge will be explained referring to FIGS. 1
and 2. FIG. 1 is an external perspective view showing an ink
cartridge prior to loading in the inkjet recording apparatus and
FIG. 2 is a cross-sectional view of the ink cartridge.
[0156] The ink cartridge 7 contains an ink absorber 42 which has
absorbed an ink of predetermined color in the cartridge main body
41 as shown in FIG. 2. The cartridge main body 41 is formed by
bonding or depositing the upper lid member 44 to the upper opening
of case 43 having wide opening in upper part and may be made of
resin molding, for example. Moreover, the ink absorber 42 is formed
of porous body such as urethane foam, etc. and the ink is absorbed
after it is compressed and inserted in the cartridge main body
41.
[0157] An ink feed opening 45 for feeding ink to the recording head
6 is formed on the bottom part of the case 43 of the cartridge main
body 41 and a seal ring 46 is set in the inner periphery side of
the ink feed opening 45. Furthermore, an air opening 47 is formed
on the upper lid member 44. A cap member 50 is attached to the
cartridge main body 41 to plug up the ink feed opening 45 and to
prevent inner ink leakage caused by compressive deformation of the
case 43 which is pressurized by wide side wall during handling for
loading or transporting or vacuum packaging prior to loading.
[0158] The air opening 47 is sealed by affixing the seal member 55
in the form of film with an oxygen transmission rate of 100
ml/m.sup.2 or more to the upper lid member 44 as shown in FIG. 1.
By sealing the air opening 47 with the seal member 55 with an
oxygen transmission rate of 100 ml/m.sup.2 or more and by packing
the ink cartridge 7 under depressurized condition using a packing
member such as aluminum laminated film having no air permeability,
ink deaeration is improved even when the air is dissolved in the
ink during ink filling or because of the air in the space A (FIG.
2) formed between the ink absorber 42 and the cartridge main body
41. It is because the air inside the ink is evacuated to the space
formed between packing materials outside of the cartridge main body
41 having high degree of vacuum through the seal member 55.
[0159] The ink cartridge of the present invention contains the
recording ink (ink set) of the present invention and can be used by
loading in various inkjet recording apparatuses as detachable. It
is particularly preferable to be used as loaded in the inkjet
recording apparatus of the present invention described later as
detachable.
(Inkjet Recording Apparatus and Inkjet Recording Method)
[0160] The inkjet recording apparatus of the present invention
contains at least an ink drop discharge unit and other units such
as stimulation generation unit, control unit, and the like as
necessary.
[0161] The inkjet recording method of the present invention
contains at least ink drop discharge and other steps such as
stimulation generation, control, and the like as necessary.
[0162] The inkjet recording method of the present invention may be
preferably performed by the inkjet recording apparatus of the
present invention and the ink drop discharge may be preferably
performed by the ink drop discharge unit. Other steps may be
preferably performed by other units respectively.
--Ink Drop Discharge and Ink Drop Discharge Unit--
[0163] The ink drop discharge is a step in which the recording ink
is discharged by stimulation applied to the recording ink to form
an image. The ink drop discharge unit is configured to discharge
the recording ink by applying stimulation to the recording ink to
form an image. The ink drop discharge unit is not particularly
limited and may be selected accordingly and examples include
various nozzles for ink discharge.
[0164] The stimulation may be generated through above-noted
stimulation generation unit, for example. The stimulation is not
particularly limited and may be selected accordingly. Examples
include heat (temperature), pressure, vibration, light, and the
like. These may be used alone or in combination. Among them, heat
and pressure are suitable.
[0165] Specifically, examples of the stimulation generation unit
include heating device, pressure device, piezoelectric element,
vibration generating device, ultrasonic generating device, light,
and the like, and in particular, piezoelectric actuator such as
piezoelectric element, thermal actuator based on the phase-change
of the film between liquid and vapor using electrothermal
transducer such as heating resistor, and the like, shape memory
alloy actuator based on phase-change of the metal by temperature
change, electrostatic actuator based on electrostatic power, and
the like.
[0166] The aspect of recording ink discharge is not particularly
limited and it varies depending on the stimulation. If the
stimulation is generated by "heat", such process is exemplified as
thermal energy corresponding to the recording signal is applied to
the recording ink in the recording head using a thermal head, for
example, then bubbles are generated in the recording ink through
the thermal energy, thereby injecting the recording ink from the
nozzle of the recording head in form of ink drops owing to bubble
pressure. Alternatively, if the stimulation is generated by
"pressure", such process is exemplified as a voltage is applied to
a piezoelectric element adhered to the place so-called pressure
room in the ink flowing passage of the recording head, causing the
piezoelectric element to be deflected, thereby reducing the volume
of the pressure room and injecting the recording ink from the
nozzle of the recording head in form of ink drops.
[0167] The ink drops of the recording ink discharged is preferably
3 pl to 40 pl in size at an injection speed of 5 m/s to 20 m/s,
drive frequency of 1 kHz or more and resolution of 300 dpi or
more.
[0168] In addition, the control unit is not particularly limited as
long as it can control the individual unit efficiently and may be
selected accordingly. Examples thereof include sequencer, computer,
and the like.
[0169] Next, it is possible to decide the scanning direction during
recording corresponding to the duty of image data in the present
invention.
[0170] The ink drops of these four colors are applied to a
recording medium with an appropriate balance and other colors are
created by mixing during operation of full-color recording in an
inkjet recording apparatus forming an image using the ink of four
colors. When an image of green (G) is recorded, cyan (C) and yellow
(Y) are mixed for recording. In other words, C and Y dots are put
onto the same recording spot.
[0171] The condition of applied ink drop when an ink drop is
discharged onto the regular paper using a recording head is shown
in FIGS. 5A and 5B. FIG. 5A is a cross-sectional view of the
regular paper when recording in the outward direction (C.fwdarw.Y)
and FIG. 5B is a cross-sectional view when recording in the
homeward direction (Y.fwdarw.C). In FIG. 5A, the first recorded C
covers the surface and next recorded Y penetrates deeper than
C.
[0172] On the other hand, the first recorded Y covers the surface
and the next recorded C penetrates deeper than Y. When these
records are observed from the surface, 5A looks more cyanish green
and 5B looks more yellowish green. The same CY-mixed color can be
completely different color for reciprocating recording and
nonuniformity color occurs alternatively at every linefeed as shown
in FIG. 6.
[0173] In general, the level at which a person can recognize the
color difference of an adjacent image expressed by following
Equation 1 is said to be approximately 1.0.
.DELTA.E*= {square root over
(.DELTA.L*.times..DELTA.L*+.DELTA.a*.times..DELTA.a*+.DELTA.b*.times..DEL-
TA.Ab*)} Equation 1
[0174] From FIG. 7, it turns out that the color difference
increases as the ink duty rate increases for all R, B and G and
when the color difference .DELTA.E* is 1.0 or more, R, B and G are
in high density region with R being approximately 75%, G being
approximately 35% and B being approximately 57%.
[0175] It is possible to eliminate bidirectional color difference
without slowing the printing speed as much as possible by
performing one directional printing in the recording region of high
ink duty with distinguishable color difference and performing
bidirectional printing in the recording region of low ink duty with
undistinguishable color difference. For example, it is possible to
effectively pursue a high-speed printing and elimination of
bidirectional color difference simultaneously if one directional
printing is performed at 75% or more duty and bidirectional
printing is performed at 75% or less duty. This threshold value
differs depending on the ink composition and color material and it
is preferable to be set for each model.
[0176] Practically, it is decided that if the bidirectional color
difference is distinguishable or not by the color difference near
boundary of scanning instead of average color difference in total.
It is because of the vision property of human which is sensitive to
the color difference of adjacent region but is insensitive to the
color difference of a portion at some distance. It is therefore
preferable to detect the boundary region of scanning and other
region separately and decide on bidirectional or one directional
recording.
[0177] FIG. 8A shows a calculation method of the ink duty in
predetermined region of the image data in the image region
(scanning region: also called "1 band") of scan width of recording
head.times.300 dots (recording width of recording head) prior to
recording when two windows as multiple windows are used. A window
B62 is prepared to calculate the duty near boundary of image region
(boundary with different band) and the ink duty in the window is
calculated from the image data in the window by scanning the window
through the image region.
[0178] A window A61 is for calculation of the ink duty of entire
recording width of recording head at 600 dots per inch=600 dpi of
resolution in lateral direction (duty of entire width in the
transporting direction of a recording medium in the image region)
and the size of the window in here is supposed to be 300
dots.times.128 dots.
[0179] A window B is for calculation of the ink duty of region near
boundary of image region (boundary with adjacent band) in which
recording is performed by each scan and the size of the window in
here is supposed to be 32 dots.times.128 dots.
[0180] The window B62 should be set at a position from which the
ink duty near boundary between bands can be read out. It is
preferably the region from which the ink duty in the range from the
boundary 63 to the site 0.5 mm to 5 mm away from the boundary 63 is
read out. It is also desirable to set a window at a position which
includes the ink duty of the dot closest to the boundary 63;
however, the site can be a several dots away from the boundary
63.
[0181] It is desirable for the window A61 to have a width from
which duty of entire width (band width) in the direction crossing
the scanning direction of the head is readable; however, it can be
set at a position a several dots away from the boundary 63 because
only the ink duty of band width is wanted to be reflected.
[0182] Moreover, lengths of the windows A and B in the scanning
direction of the head (length direction of the band) are not
limited to 128 dots and may be the lengths with which the ink duty
of the window is easily calculated.
[0183] The number of image data with which calculation is performed
differs between windows A and B. In window A, calculation is
performed with relatively large number of image data to obtain
average density distribution of the scanning region compared to the
window B where calculation is performed with relatively small
number of image data to obtain local density distribution of the
boundary.
[0184] However, this relation in number of image data is not
mandatory because the same effect can be obtained by assigning a
window to a site where boundary and band width are reflected as
described above.
[0185] The calculation of the ink duty in these windows is
performed by using the image data memorized in the buffer of
recording control section.
[0186] The scanning method of a window can be either a scanning
method in which an ink duty is calculated by altering each window
one line at a time in the scanning direction of the recording head
(length direction of band) as shown in FIG. 8B or a scanning method
in which an ink duty is calculated by altering each window by
length of each window at a time (128 dots in lateral direction in
this case) in the length direction of the band as shown in FIG.
8C.
[0187] Each ink duty Dc of cyan image, ink duty Dm of magenta
image, ink duty Dy of yellow image in the window is counted and the
total of Dc, Dm and Dy would be an ink duty in the window at a
window position.
[0188] The threshold value of the ink duty of each window is set at
100% for window A and 75% for window B. 100% ink duty is defined as
a condition in which the number of color ink dot recorded in a
pixel position of 1/600 inch.times. 1/600 inch is one. For example,
an image of cyan 100% means that the region is full of cyan dots
and 200% means a solid image of blue which is full of cyan and
magenta dots.
[0189] More specifically, an ink duty is a ratio of applied color
material in a single recording region and it is 100% maximum for
the primary color and 200% maximum for the secondary color.
[0190] When the condition in which the ink duty of window A in the
entire position of the recording region prior to recording is 100%
or less and the ink duty of window B in all positions is 75% or
less is satisfied, the recording speed is increased by performing
in both direction of outward and homeward scan (reciprocation
recording). When one of the condition is not satisfied, uneven
printing is decreased by performing recording with one of outward
or homeward scan (one directional recording).
[0191] Meanwhile, the threshold value of the ink duty of window A
is set smaller than the threshold value of the window B because the
ink duty of the window B is near boundary and is likely to be
distinguishable with relatively less unevenness. Contrary, if the
threshold value of the window A is set strictly small, the ratio of
one directional recording becomes too much causing recording speed
deterioration.
[0192] FIG. 9 is a flow chart showing above operation and the
recording of the first scan (n=1) of the recording head is
performed corresponding to the image data in step 1. In the
example, the scanning direction starts from the home position of
the recording head, however, it is not limited to the example.
[0193] Next, it is set to n=n+1 for transition to the next scan
(recording of the second band) in step 2.
[0194] The ink duty of windows A and B at a position of next scan
(the second scan, for example) is calculated from the ink duty of
each color in step 3 and it is determined if the ink duty of the
window A is 100% or less in step 4. If it is 100% or less, it is
proceeded to step 5 and if it is more than 100%, it is proceeded to
step 7. When it is 100% or less, it is then determined if the ink
duty of window B is 75% or less in step 5. If it is 75% or less, it
is proceeded to step 6 and if it is more than 75%, it is proceeded
to step 7. The reciprocation recording operation, that is the
recording in opposite of previous recording direction (the first
scan in this case) is set to perform in step 6. The one directional
printing operation, that is the recording in the same direction of
previous recording, is set to perform in step 7.
[0195] After step 6, it is determined if all the shift in "n" band
of each window is finished in step 8 and the window is shifted to
the next position if it is not finished in step 9. It is then
returned to step 3 after shifting and readout calculation is
performed to see if there is a portion in which the ink duty
exceeds the standard value until all the shift is finished.
[0196] When there is no window exceeding standard value after all
the shift of window is finished, a recording in opposite direction
with the (n-1).sup.th band is performed (step 10).
[0197] When a recording in the same direction of previous band is
set to perform in step 7, a recording is performed without
calculating the ink duty of next window in the example.
[0198] These operations are repeated until all the recording is
finished.
[0199] Next, an image forming method on a recording medium by
containing the recording ink of the present invention in a ink
cartridge, loading the ink cartridge in an inkjet printer and
discharging the recording ink from a fine discharge opening as a
liquid drop will be explained referring to drawings.
[0200] FIG. 3 is an outlined front view of an exemplary serial-type
inkjet recording apparatus having an ink cartridge equipped with a
recording ink compartment containing the recording ink of the
present invention.
[0201] In the mechanical section of the inkjet recording apparatus,
the main guide rod 3 and the sub guide rod 4 are bridged laterally
between the side panels 1 and 2 in almost horizontal position and
the carriage unit 5 is supported by the main guide rod 3 and the
sub guide rod 4 in the main scanning direction as slidable.
[0202] Each of four head 6 which discharges yellow (Y) ink, magenta
(M) ink, cyan (C) ink and black (Bk) ink respectively, is mounted
on the carriage unit 5 with each discharge side (nozzle side) 6a
facing downward. Four ink cartridges 7y, 7m, 7c and 7k as ink
feeders for each color are mounted on the upper side of the head 6
of the carriage unit 5 as exchangeable.
[0203] The carriage unit 5 is then attached to the timing belt 11
which is extended between the drive pulley (drive timing pulley) 9
rotated by the main scanning motor 8 and the sub-drive pulley (idle
pulley) 10 to control the drive of the main scanning motor 8 and
the carriage 5, that is, four head 6 is moved into the main
scanning direction.
[0204] Furthermore, by setting up the sub-frames 13 and 14 on the
floor plate 12 which hooks up the side plates 1 and 2, the
transport roller 15, by which the paper 16 is transported in the
sub-scanning direction crossing the main scanning direction at a
right angle, is placed rotatable between the sub-frames 13 and 14.
And the sub-scanning motor 17 is placed on the side of the
sub-frame 14 and the gear 18 is fixed on the rotation axis of the
sub-scanning motor 17 and the gear 19 is fixed onto the axis of the
transport roller 15 in order to transmit the rotation of the
sub-scanning motor 17 to the transport roller 15.
[0205] The restorative system for liability 21 of the head 6
(hereafter referred to as "sub-system") is placed between the side
plate 1 and the sub-frame 12. In the sub-system 21, the holder 23,
which keeps the four cap units 22 for capping the discharge side of
each head 6, is kept by the link member 24 as swingable 5 and the
carriage unit 5 touches the catching part 25 mounted on the holder
23 by the movement in the main scanning direction. The holder 23 is
lifted up following with the movement of the carriage unit 5 and
the discharge side 6a of inkjet head 6 is capped with the cap unit
22 and the carriage unit 5 is moved further into the printing area.
The holder 23 is then lifted down with the movement of the carriage
unit 5 and the cap unit 22 is separated from the discharge side 6a
of the inkjet head 6.
[0206] The cap unit 22 is connected with the suction pump 27 via
the suction tube 26 while simultaneously being communicated with
air via air open tube and air open bulb by forming an air opening.
The suction pump 27 discharges suctioned waste solution into the
waste solution storage tank which is not shown in figures via drain
tubes, etc.
[0207] The wiper blade 28, as a wiping unit which may be of fabric,
foaming or elastic members such as rubber, and the like with which
the discharge side 6a of the inkjet head 6 is wiped, is mounted to
the blade arm 29 on the side of the holder 23. The blade arm 29 is
set up as swingable and it is swinged by the rotation of the cam
that is rotated by the drive unit which is not shown in
figures.
[0208] FIG. 4 shows a configuration example of the ink containing
part wherein the ink of the present invention is contained and the
recording cartridge (recording unit) equipped with a head part for
discharging ink drops. The recording unit will be explained
below.
[0209] The recording unit 30 is a serial type, and the main part is
lined up with the head 6, ink tank 33 containing the ink fed from
the head 6 and the cap member 34 which seals the inside of the ink
tank 33. A lot of nozzle 32 for discharging ink is formed on the
head 6 of the recording unit 30. The ink is fed from the ink tank
33 to the common liquid chamber (not shown in figures) via ink
feeding tube (not shown) and discharged from the nozzle 32
corresponding to the electric signals entered by the electrode 31
from the recording apparatus body. This type of recording unit 30
is structurally favorable for affordable head powered by thermal
energy which is referred to as thermal-type or bubble-type.
[0210] Because the ink of the present invention excels in wetting
ability in the recording method such as bubble or thermal type,
etc., the wetting ability to the thermal element is improved,
discharge and frequency stability can be obtained and it is highly
safe and extremely suitable.
[0211] Although examples are only applied to a serial type inkjet
recording apparatus hereinbefore, the ink of the present invention
is also applicable for other recording apparatuses equipped with
line head, wherein the nozzles are aligned in a voluntary order
such as zigzag, etc. and the density is concentrated to a degree as
same as or of a fraction of the intended image resolution and
aligned more wider than the recording medium.
[0212] Although the example described here was an example applied
to a serial-type (shuttle-type) inkjet recording apparatus with
scanning carriage, it can be also applied to a line-type inkjet
recording apparatus equipped with line head.
[0213] The inkjet recording apparatus and the inkjet recording
method of the present invention can be applied to various inkjet
recordings and can be suitably used for inkjet recording printer,
facsimile, copier, complex machine of printer/facsimile/copier, and
the like.
(Ink Record)
[0214] The ink record of the present invention is an ink record
recorded by the ink jet recording apparatus and the inkjet
recording method of the present invention. The ink record of the
present invention contains an image formed on a recording medium
using the recording ink of the present invention.
[0215] The recording medium is not limited and may be selected
accordingly and examples thereof include regular paper, gloss
paper, special paper, cloth, film, overhead projection (OHP) sheet,
and the like. These may be used alone or in combination.
[0216] The ink record may be suitably used for various purposes as
a material on which various prints and/or images of high-quality
and excellent stability over time with no blur is recorded.
[0217] Conventional problems can be solved by the present invention
which enables to provide a recording ink and ink set in which
diketopyrrolopyrrole red pigment and phthalocyanin green pigment
with excellent color development can be stably dispersed in an
aqueous medium; properties remain the same after long storage; and
are suitable as red and green inks with appropriate discharge
stability by inkjet; and ink cartridge, ink record, inkjet
recording apparatus and inkjet recording method which utilize the
recording ink respectively.
EXAMPLE
[0218] Herein below, with referring to Examples and Comparative
Examples, the invention is explained in detail and the following
Examples and Comparative Examples should not be construed as
limiting the scope of this invention. All percentages and parts are
by mass unless indicated otherwise.
Preparation Example 1
Preparation of Yellow Ink
TABLE-US-00001 [0219]<Mill Base Formula> First yellow 031 18
parts (C.I. pigment yellow 74 loaded with 30% moisture by
Dainichiseika Color & Chemicals Mfg. Co., Ltd.) polyoxyethylene
laurylether expressed by following 5 parts Structural Formula as a
nonionic surfactant
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H Structural Formula
deionized water 77 parts <Ink Formula> above-produced mill
base 100 parts glycerin 10 parts 1,3-butanediol 30 parts
2,2,4-trimethyl-1,3-pentanediol 4 parts surfactant expressed by
following Structural 4 parts Formula
C.sub.13H.sub.27--O--(CH.sub.2CH.sub.2O).sub.3CH.sub.2COONa
Structural Formula Proxel LV (antiseptic/antifungal agent) 0.2
parts deionized water 51.8 parts
[0220] Next, polyoxyethylene laurylether was dissolved in deionized
water and above pigment was mixed and moistened to a satisfactory
extent. Zircornia beads of 0.5 mm diameter was filled into a
kneading apparatus, DYNO-Mill KDL A by W. A. Bachofen of
Switzerland, and knead-mixed at 2,000 rpm for 2 hours to obtain a
mill base.
[0221] Next, glycerin, 1,3-butanediol,
2,2,4-trimethyl-1,3-pentanediol, surfactant expressed by above
Structural Formula, and Proxel LV were dissolved in deionized water
to produce a vehicle, and the vehicle was mixed with the mill base
and then filtered by Tefron.TM.-made filter of 1 .mu.m average pore
diameter to produce a yellow ink for inkjet recording with average
particle diameter of 75 nm. The particle diameter was measured by a
particle diameter measuring machine, UPA150 by Microtrac, Inc.
Preparation Example 2
Preparation of Magenta Ink
TABLE-US-00002 [0222]<Mill Base Formula> HOSTAFINE MAGENTA
E-PT 15 parts (C.I. pigment red 122 by Clariant (Japan) K.K.)
polyoxyethylene laurylether expressed by following 5 parts
Structural Formula as a nonionic surfactant
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H Structural Formula
deionized water 80 parts
[0223] A mill base was prepared using above mill base formula and
method similar to the one used for yellow ink of Preparation
Example 1 to produce a magenta ink for inkjet recording with an
average particle diameter of 120 nm using the ink formula similar
to the one used for yellow ink of Preparation Example 1.
Preparation Example 3
Preparation of Cyan Ink
TABLE-US-00003 [0224]<Mill Base Formula> IRGALITE Blue 8700
13 parts (C.I. pigment blue 15:3 by Ciba Specialty Chemicals K.K.)
polyoxyethylene laurylether expressed by following 5 parts
Structural Formula as a nonionic surfactant
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H Structural Formula
deionized water 82 parts
[0225] A mill base was prepared using above mill base formula and
method similar to the one used for yellow ink of Preparation
Example 1 to produce a cyan ink for inkjet recording with an
average particle diameter of 105 nm using the ink formula similar
to the one used for yellow ink of Preparation Example 1.
Example 1
Preparation of Red Ink
TABLE-US-00004 [0226]<Mill Base Formula> IRGZIN DPP Red BTR
14 parts (C. I. pigment red 254 by Ciba Specialty Chemicals K.K.)
polyoxyethylene laurylether expressed by following 5 parts
Structural Formula C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H
Structural Formula deionized water 81 parts <Ink Formula>
above-produced mill base 100 parts glycerin 10 parts 1,3-butanediol
30 parts 2-ethyl-1,3-hexanediol 4 parts surfactant expressed by
following Structural 4 parts Formula
C.sub.13H.sub.27--O--(CH.sub.2CH.sub.2O).sub.3CH.sub.2COONa
Structural Formula Proxel LV (antiseptic/antifungal agent) 0.2
parts deionized water 51.8 parts
[0227] Next, polyoxyethylene laurylether was dissolved in deionized
water and above pigment was mixed and moistened to a satisfactory
extent. Zircornia beads of 0.5 mm diameter was filled into a
kneading apparatus, DYNO-Mill KDL A by W. A. Bachofen of
Switzerland, and knead-mixed at 2,000 rpm for 2 hours to obtain a
mill base.
[0228] Next, glycerin, 1,3-butanediol, 2-ethyl-1,3-hexanediol,
surfactant expressed by above Structural Formula, and Proxel LV
were dissolved in deionized water to produce a vehicle, and the
vehicle was mixed with the mill base and then filtered by
Tefron.TM.-made filter of 1 .mu.m average pore diameter to produce
a red ink with a volume average particle diameter of 156 nm.
[0229] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 1 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
was performed using only all-dot (100%) red ink for red color.
Example 2
Preparation of Red Ink
TABLE-US-00005 [0230]<Mill Base Formula> IRGZIN DPP Red BTR
14 parts (C.I. pigment red 254 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural Formula as 5 parts an
anionic surfactant Structural Formula (A) ##STR00008## deionized
water 81 parts
[0231] Next, the dispersant expressed by above Structural Formula
(A) which is an anionic surfactant was dissolved in deionized water
to produce a mill base similarly to Example 1. And an red ink with
a volume average particle diameter of 102 nm was produced using the
ink formula similarly to Example 1.
[0232] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 2 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
was performed using only all-dot (100%) red ink for red color.
Example 3
Preparation of Ink Set
[0233] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd.
[0234] Next, the red ink prepared in Example 2 was filled in a
cartridge and loaded in the place for cyan ink. And the printing of
red ink was performed at each ink duty of 50%, 90% and 100%. The
ink ratio of each ink duty was 95% red ink and 5% yellow ink for
50% duty, 100% red ink for 90% duty and 95% red ink and 5% magenta
ink for 100% duty.
Example 4
Preparation of Green Ink
TABLE-US-00006 [0235]<Mill Base Formula> IRGALITE Green 6G 15
parts (C.I. pigment green 36 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural Formula 6 parts (A) as
an anionic surfactant Structural Formula (A) ##STR00009## deionized
water 79 parts <Ink Formula> above-produced mill base 100
parts glycerin 15 parts 1,3-butanediol 30 parts
2,2,4-trimethyl-1,3-pentanediol 4 parts surfactant expressed by
following Structural 4 parts Formula Structural Formula
C.sub.13H.sub.27--O--(CH.sub.2CH.sub.2O).sub.3CH.sub.2COONa Proxel
LV (antiseptic/antifungal agent) 0.2 parts deionized water 46.8
parts
[0236] Next, a mill base was prepared using above mill base formula
and method similarly to Example 1 and a green ink with a volume
average particle diameter of 123 nm was produced using above ink
formula and method similarly to Example 1.
[0237] The cyan ink of Preparation Example 3 and the yellow ink of
Preparation Example 1 were filled in a cartridge and loaded in the
prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the green ink prepared in Example 4 was filled
in a cartridge and loaded in the place for magenta ink. And the
printing was performed using only all-dot (100%) green ink for
green color.
Example 5
TABLE-US-00007 [0238]<Mill Base Formula> IRGALITE Green GFNP
14 parts (C.I. pigment green 7 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural 5 parts Formula
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H Structural Formula
deionized water 81 parts <Ink Formula> mill base 100 parts
glycerin 12 parts propylene glycol 36 parts 2-ethyl-1,3-hexanediol
4 parts surfactant expressed by following Structural 4 parts
Formula C.sub.13H.sub.27--O--(CH.sub.2CH.sub.2O).sub.3CH.sub.2COONa
Structural Formula Proxel LV (antiseptic/antifungal agent) 0.2
parts deionized water 43.8 parts
[0239] The dispersant expressed by above Structural Formula was
dissolved in deionized water and above pigment was mixed and
moistened to a satisfactory extent. Zircornia beads of 0.5 mm
diameter was filled into a kneading apparatus, DYNO-Mill KDL A by
W. A. Bachofen of Switzerland, and knead-mixed at 2,000 rpm for 2
hours to obtain a mill base.
[0240] Next, glycerin, propylene glycol, 2-ethyl-1,3-hexanediol,
surfactant expressed by above Structural Formula, and Proxel LV
were dissolved in deionized water to produce a vehicle, and the
vehicle was mixed with the mill base and then filtered by
Tefron.TM.-made filter of 1 .mu.m average pore diameter to produce
a green ink for inkjet recording with an average particle diameter
of 106 nm.
[0241] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, prepared green ink was filled in a cartridge
and loaded in the place for cyan ink. And the printing was
performed using only all-dot (100%) green ink for green color.
Example 6
TABLE-US-00008 [0242]<Mill Base Formula> IRGALITE Green 6G 14
parts (C.I. pigment green 36 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural 5 parts Formula
Structural Formula
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.11SO.sub.3NH.sub.4
deionized water 81 parts <Ink Formula> above-produced mill
base 100 parts glycerin 14 parts 1,6-hexanediol 32 parts
2-ethyl-1,3-hexanediol 4 parts Pesresin A-520 2.8 parts
(water-dispersible polyester resin with mass-average molecular
weight of 14,000 and solid content of 30% by Takamatsu Oil &
Fat Co, Ltd.) FT-150 4 parts (fluorochemical surfactant expressed
by following Structural Formula (16) by Neos Co., Ltd.) Structural
Formula (16) ##STR00010## In above Structural Formula (16), Rf1 is
one of the compounds expressed by following Structural Formulas
(16a) and (16b). Structural Formula ##STR00011## Structural Formula
##STR00012## Proxel LV (antiseptic/antifungal agent) 0.2 parts
deionized water 43.0 parts
[0243] The dispersant expressed by above Structural Formula was
dissolved in deionized water to produce a mill base as similar to
Example 5.
[0244] Next, glycerin, 1,6-hexanediol, 2-ethyl-1,3-hexanediol,
Pesresin A-520, FT-150 and Proxel LV were dissolved in deionized
water to produce a vehicle, and the vehicle was mixed with the mill
base and then filtered by Tefron.TM.-made filter of 1 .mu.m average
pore diameter to produce a green ink for inkjet recording with an
average particle diameter of 99 nm.
[0245] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the green ink prepared in Example 6 was filled
in a cartridge and loaded in the place for cyan ink. And the
printing was performed using only all-dot (100%) green ink for
green color.
Example 7
TABLE-US-00009 [0246]<Mill Base Formula> IRGAZIN DPP Rubine
TR 15 parts (C.I. pigment red 264 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural Formula 5 parts (17)
Structural Formula (17) ##STR00013## deionized water 80 parts
<Ink Formula> above-produced mill base 100 parts glycerin 15
parts 1,5-pentanediol 30 parts 2,2,4-trimethyl-1,3-pentanediol 4
parts FT-400SW 5 parts (fluorochemical surfactant with solid
content of 50% expressed by following Structural Formula (18) by
Neos Co., Ltd.) Structural Formula (18) ##STR00014## In above
Structural Formula (18), Rf1 is one of the compounds expressed by
above Structural Formulas (16a) and (16b). Proxel LV
(antiseptic/antifungal agent) 0.2 parts deionized water 45.8
parts
[0247] The dispersant expressed by above Structural Formula was
dissolved in deionized water to produce a mill base similarly to
Example 5.
[0248] Next, glycerin, 1,5-pentanediol,
2,2,4-trimethyl-1,3-pentanediol, FT-400SW and Proxel LV were
dissolved in deionized water to produce a vehicle, and the vehicle
was mixed with the mill base and then filtered by Tefron.TM.-made
filter of 1 .mu.m average pore diameter to produce a red ink for
inkjet recording with an average particle diameter of 87 nm.
[0249] The cyan ink of Preparation Example 3 and the yellow ink of
Preparation Example 1 were filled in a cartridge and loaded in the
prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 7 was filled in
a cartridge and loaded in the place for magenta ink. And the
printing was performed using only all-dot (100%) red ink for red
color.
Example 8
TABLE-US-00010 [0250]<Mill Base Formula> IRGZAIN DPP Red BTR
(C.I. pigment red 254 by Ciba 15 parts Specialty Chemicals K.K. )
dispersant expressed by following Structural Formula 6 parts (13)
Structural Formula (13)
C.sub.12H.sub.25--O--(CH.sub.2CH.sub.2O).sub.43H deionized water 79
parts <Ink Formula> above-produced mill base 100 parts
glycerin 12 parts triethylene glycol 32 parts
2,2,4-trimethyl-1,3-pentanediol 4 parts PF-151N 2 parts
(fluorochemical surfactant expressed by following Structural
Formula (19) by Omnova Solutions, Inc.) Structural Formula (19)
##STR00015## In above Structural Formula (19), Rf1 represents one
of CF.sub.3 and CF.sub.2CF.sub.3. "n" represents "8". "m"
represents an integer of 20 or less. "p" represents an integer of 4
or less. WEM-321U 7 parts (acryl-urethanecore shell type aqueous
emulsion having self-crosslinking property after printing and
drying with the minimum film-forming temperature of 10.degree. C.,
average particle diameter of 100 nm, solid content of 38% and
acryl/urethane ratio of 50/50 by Taisei Finechemical Co., Ltd.)
Proxel LV (antiseptic/antifungal agent) 0.2 parts deionized water
42.8 parts
[0251] The dispersant expressed by above Structural Formula was
dissolved in deionized water to produce a mill base as similar to
Example 5.
[0252] Next, glycerin, triethylene glycol,
2,2,4-trimethyl-1,3-pentanediol, PF-151N, WEM-321U and Proxel LV
were dissolved in deionized water to produce a vehicle, and the
vehicle was mixed with the mill base and then filtered by
Tefron.TM.-made filter of 1 .mu.m average pore diameter to produce
a red ink for inkjet recording with an average particle diameter of
95 nm.
[0253] The cyan ink of Preparation Example 3 and the yellow ink of
Preparation Example 1 were filled in a cartridge and loaded in the
prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 8 was filled in
a cartridge and loaded in the place for magenta ink. And the
printing was performed using only all-dot (100%) red ink for red
color.
Example 9
TABLE-US-00011 [0254]<Mill Base Formula> IRGZAIN DPP Red BTR
15 parts (C.I. pigment red 254 by Ciba Specialty Chemicals K.K.)
dispersant expressed by following Structural Formula 6 parts (20)
Structural Formula (20) ##STR00016## deionized water 79 parts
<Ink Formula> above-produced mill base 100 parts glycerin 12
parts 3-methyl-1,3-butanediol 32 parts 2-ethyl-1,3-hexanediol 4
parts JC-05 10 parts (styrene-acryl copolymer with mass-average
molecular weight of 20,000 and solid content of 21% by Seiko PMC
Corp.) FT-110 4 parts (a fluorochemical surfactant expressed by
following Structural Formula (21) by Neos Co., Ltd.) Structural
Formula (21) ##STR00017## In above Structural Formula (21), Rf1 is
one of the compounds expressed by above Structural Formulas (16a)
and (16b). Proxel LV (antiseptic/antifungal agent) 0.2 parts
deionized water 37.8 parts
[0255] The dispersant expressed by above Structural Formula (20)
was dissolved in deionized water to produce a mill base as similar
to Example 5.
[0256] Next, glycerin, 3-methyl-1,3-butanediol,
2-ethyl-1,3-hexanediol, JC-05, FT-110 and Proxel LV were dissolved
in deionized water to produce a vehicle, and the vehicle was mixed
with the mill base and then filtered by Tefron.TM.-made filter of 1
.mu.m average pore diameter to produce a red ink for inkjet
recording with an average particle diameter of 95 nm.
[0257] The cyan ink of Preparation Example 3 and the yellow ink of
Preparation Example 1 were filled in a cartridge and loaded in the
prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 9 was filled in
a cartridge and loaded in the place for magenta ink. And the
printing was performed using only all-dot (100%) red ink for red
color.
Example 10
[0258] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 9 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
of red ink was performed at each ink duty of 50%, 90% and 100%. The
ink ratio of each ink duty was 95% red ink and 5% yellow ink for
50% duty, 100% red ink for 90% duty and 95% red ink and 5% magenta
ink for 100% duty.
Example 11
[0259] A mill base was prepared similarly to Example 1 except for
altering the dispersant of Example 1 to lauryl ether sulfate sodium
salt expressed by following Structural Formula (22) to produce a
recording ink.
C.sub.12H.sub.25--O--SO.sub.3Na Structural Formula (22)
[0260] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 1 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
was performed using only all-dot (100%) red ink for red color.
Example 12
[0261] A mill base was prepared similarly to Example 1 except for
altering 2-ethyl-1,3-hexanediol of Example 1 to
3-methyl-2,4-heptanediol and a recording ink was produced using the
mill base.
[0262] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 1 was filled in
a cartridge and loaded in the place for cyan ink.
[0263] And the printing was performed using only all-dot (100%) red
ink for red color.
Example 13
[0264] A mill base was prepared similarly to Example 1 except for
altering glycerin and 1,3-butanediol of Example 1 to
N-methyl-2-pyrrolidone to produce a recording ink.
[0265] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 1 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
was performed using only all-dot (100%) red ink for red color.
Example 14
[0266] A mill base was prepared similarly to Example 6 except for
altering Pesresin A-520 of Example 6 to Takelac W-5025 (a
water-dispersible polyurethane resin with mass-average molecular
weight of 18,000 and solid content of 30% by Mitsui Takeda
Chemicals, Inc.) to produce a recording ink.
[0267] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the green ink prepared in Example 6 was filled
in a cartridge and loaded in the place for cyan ink. And the
printing was performed using only all-dot (100%) green ink for
green color.
Comparative Example 1
[0268] The cyan ink of Preparation Example 3, the magenta ink of
Preparation Example 2 and the yellow ink of Preparation Example 1
were filled in a cartridge and loaded in the prescribed place in
the inkjet printer, IPSIO G707 by Ricoh Company, Ltd. to perform
printing.
Comparative Example 2
[0269] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. And equal amount of each yellow ink of Preparation
Example 1 and the magenta ink of Preparation Example 2 were mixed
to produce a red ink. The prepared red ink was then filled in a
cartridge and loaded in the place for cyan ink to perform
printing.
Comparative Example 3
[0270] A red ink for inkjet recording with an average particle
diameter of 106 nm was produced using mill base formula and ink
formula as similar to Example 9 except for altering the pigment of
Example 9 to CROMOPHTAL Red A2B (C. I. pigment red 177,
dianthraquinonyl red pigment by Ciba Specialty Chemicals K.K.).
[0271] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 9 was filled in
a cartridge and loaded in the place for cyan ink. And the printing
was performed using only all-dot (100%) red ink for red color.
Comparative Example 4
[0272] A recording ink was produced using a mill base prepared
similarly to Example 1 except for not using
2-ethyl-1,3-hexanediol.
[0273] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd. Next, the red ink prepared in Example 1 was filled in
a cartridge and loaded in the place for cyan ink. And printing was
performed using only all-dot (100%) red ink for red color.
Comparative Example 5
Preparation of Ink Set
[0274] The magenta ink of Preparation Example 2 and the yellow ink
of Preparation Example 1 were filled in a cartridge and loaded in
the prescribed place in the inkjet printer, IPSIO G707 by Ricoh
Company, Ltd.
[0275] Next, the red ink prepared in Comparative Example 3 was
filled in a cartridge and loaded in the place for cyan ink. And the
printing of red ink was performed at each ink duty of 50%, 90% and
100%. The ink ratio of each ink duty was 95% red ink and 5% yellow
ink for 50% duty, 100% red ink for 90% duty and 95% red ink and 5%
magenta ink for 100% duty.
<Storage Stability (Viscosity)>
[0276] The rate of viscosity change (%) of each recording ink
produced in Examples 1 to 14 and Comparative Examples 1 to 5 when
stored in a tightly sealed condition at 50.degree. C. for one month
is shown in Table 1. A viscometer, RC-500 by Toki Sangyo Co., Ltd.
was used for measuring viscosity.
<Storage Stability (Particle Diameter)>
[0277] The rate of average particle diameter change (%) of each
recording ink produced in Examples 1 to 14 and Comparative Examples
1 to 5 when stored in a tightly sealed condition at 50.degree. C.
for one month is shown in Table 1. A particle size analyzer, UPA150
by Microtrac, Inc. was used for measuring particle diameter.
<Discharge Stability>
[0278] Each recording ink produced in Examples 1 to 14 and
Comparative Examples 1 to 5 was filled in the inkjet printer, IPSIO
G707 by Ricoh Company, Ltd. and ability to recover no matter how
long printing is halted without capping or cleaning during printing
operation was investigated. And its reliability was determined on
how long it takes until the ejection direction is misaligned or the
mass of discharged drops is changed according to the following
evaluation standard.
[Evaluation Standard]
[0279] A: 600 seconds or more
[0280] B: 60 seconds or more and less than 600 seconds
[0281] C: less than 60 seconds
<Measurement of Saturation and Hue Angle>
[0282] A solid printing was performed in one direction for each
recording ink using following regular paper as paper for printing
test by using the inkjet printer, IPSIO G707 by Ricoh Company, Ltd.
Each value of luminance was measured using a reflective/color
spectrophotometric densitometer by X-Rite, Inc. after printing and
drying.
--Paper for Printing Test--
[0283] Regular paper: my paper SA by NBS Ricoh Co., Ltd. XEROX4024
by Fuji Xerox Office Supply PB Paper by Canon Inc.
<Measurement of Bidirectional Color Difference>
[0284] A solid printing was performed in both directions for each
recording ink using following regular paper as paper for printing
test by using the inkjet printer, IPSIO G707 by Ricoh Company, Ltd.
Each value of luminance was measured using a reflective/color
spectrophotometric densitometer by X-Rite, Inc. after printing and
drying. The maximum value of each measured color difference is
shown in Table 1.
--Paper for Printing Test--
[0285] Regular paper: my paper SA by NBS Ricoh Co., Ltd. XEROX4024
by Fuji Xerox Office Supply PB Paper by Canon Inc.
TABLE-US-00012 [0285] TABLE 1 Bidirectional Rate of Color Rate of
Particle Hue Angle (Red) Difference Viscosity Diameter Discharge
50% 90% 100% Saturation (Maximum Change Change Stability duty duty
duty Red Green Value) Example 1 13% 16% B 19.degree. 24.degree.
30.degree. 68.9 -- 2.5 Example 2 -1% 9% A 19.degree. 24.degree.
31.degree. 70.3 -- 2.1 Example 3 -1% 9% A 24.degree. 24.degree.
25.degree. 69.8 -- 1.9 Example 4 3% 7% A -- -- -- -- 60.1 2.0
Example 5 10% 8% A -- -- -- -- 58.0 2.6 Example 6 -1% 1% A -- -- --
-- 60.8 2.5 Example 7 6% -1% .sup. A 18.degree. 23.degree.
30.degree. 60.1 -- 2.4 Example 8 5% 3% A 20.degree. 24.degree.
32.degree. 69.7 -- 2.2 Example 9 2% 0% A 20.degree. 24.degree.
31.degree. 70.4 -- 1.9 Example 10 2% 0% A 24.degree. 25.degree.
25.degree. 70.3 -- 2.0 Example 11 21% 16% B 20.degree. 24.degree.
33.degree. 66.1 -- 2.8 Example 12 15% 9% B 21.degree. 24.degree.
33.degree. 67.9 -- 2.3 Example 13 5% -2% .sup. B 20.degree.
24.degree. 32.degree. 66.4 -- 2.5 Example 14 8% 4% A -- -- -- -- 60
2.3 Com. Example 1 not not not 24.degree. 25.degree. 25.degree.
54.3 53.8 10.1 obtained obtained obtained Com. Example 2 -2% 3% A
24.degree. 24.degree. 25.degree. 54.0 53.8 2.3 Com. Example 3 4% 1%
A 18.degree. 22.degree. 26.degree. 50.3 -- 2.5 Com. Example 4 2% 5%
A 21.degree. 23.degree. 32.degree. 56.8 -- Com. Example 5 4% 1% A
18.degree. 19.degree. 19.degree. 50 -- 2.1
INDUSTRIAL APPLICABILITY
[0286] The recording ink of the present invention excels in
discharge stability with no head clogging during printing and can
obtain high quality images with good color tone on the regular
paper as well as on an exclusive recording paper and is suitably
used for inkjet recording method forming color images. Also, it can
widely be used for regular stationeries such as aqueous pen,
aqueous marker, aqueous ballpoint pen, and the like, recording
meters and inks for pen plotter.
* * * * *